1. Field of the Invention
This invention relates to a new particle control screen assembly for a perforated pipe used in a well, to a sand filter system, and to methods of making the same.
2. Prior Art Statement
It is known to provide a particle control screen assembly for a perforated pipe used in a well, the assembly including a woven mesh filter media means disposed about the perforated pipe, and a protective wrapper means disposed about the filter media means. See the U.S. Patent to Padden, U.S. Pat. No. 5,411,084; and the U.S. Patent to Whitebay et al, U.S. Pat. No. 5,232,048.
It is also known to provide a protective wrapper means that comprises two cylindrical, spaced-apart tubes that are each provided with holes. See U.S. Patent to Fast, U.S. Pat. No. 4,064,938. The cylindrical walls of the tubes are very thick for erosion control, and although the holes of the respective cylindrical tubes are offset relative to one another, tangential flow through the holes of the outer tube allow relatively direct impingement of fluid from the outside against the filter media means. In addition, due to the thick walls and the spacing between them, this known well screen has a large outer diameter.